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T. F. TESSE.

PROCESS EUR D|M|N|SH|NG THE vlslBlLlTY 0E OBJECTS.

APPLICATION IFILED .|UNE24, 1918. I

Patented Aug. 22, 1922.

CHAI/asf acer/175.

WITNESSES THEODORE FRANCOIS TESSE, OF ST.OUEN, FRANCE, ASSIGNOR T0 SOCIETE NAUTON FRERES & DE WLARSAC, OF ST.O`UEN, SEINE, FRANCE, AND THEODORE FRANCOIS TESSE, OF PARIS, FRANCE.

PROCESS FOR DIMINISHING- THE V'ISIBILITY OF OBJECTS.

specification of Letteisratet. 'Patented Aug', 22, 1922,V

Application tiled June 24, 1918. Serial No. 241,685.

To all whom it may concern.'

Be it known that I, THnoDoRE FRANors TEssE, of No. 15 Rue des Rosiers, Saint- Guen, Seine, France, have invented an Improved Process for Diminishin the Visibility of Objects, of which the ollowing is 4a full, clear, and exact description.

This invention has for its object to provide an improved process for diminishing the visibility of objects, and more particularly the visibility of aeroplanes, seaplanes, ships, etc., for the,` purpose of rendering it diiiiculti for such objectsto be seen and located at night by means of searchlights.

The improved process consists essentially in producing uponthe object upon which the light beam is projected, a progressive extinction of the differently coloured rays constituting the said beam.

This result is eected by providing the object with two of more coats of varnish of different natures, namely, a first coat applied directly upon the object, and composed of a very opaque varnish or composition having a matte surface and a very dark colour in which black or blue predominates. Upon this first coat, one or more other coats are applied, composed of a translucent coloured varnish, the colour of which is chosen according to the nature of the source of light, in such a manner as to arrest the greater part of the rays of a projected light beam striking the object.

This combination has the elfect that when a beam of light is thrown upon an object covered with the above stated various coats of varnish or composition, a great part of the rays of which the light beam is composed 1s first of all arrested by the coat of transparent varnish, acting as a screen. Then the remainder of the light which has passed through saidv transparent coloured varnish is finally absorbed by the dark coloured matte opaque coat. In these circumstances the proportion of the light rays that is reiected bythe object is practically nil, and consequently the visibility of said object is thereby rendered very low.

The compositionof the transparent varnish and of the opaque varnish will vary according to the predominant colour in the projected rays of light.

The first coat, that is to say, that which 1s applied directly to the object, must contain opaque pigments having a very great light absorbing capacity. This first coat may consist for instance of lamp-black incorporated in a vehicle vor medium such as a fatty varnish, a coating composition of cellulose acetate, insoluble gelatine, etc. To this lamp black there may be added an opaque colouring matter such as Paris blue, ochres, Sienna earth, etc.

v The outer coat consists of a red lake preferably la red lake having a bluish ground, that is to say, having a violettinted colour when it is viewed by transmitted light, It has been found by experience that red colour, and particularly the red colouring matters of aniline have the power of absorbing Lthe greater part of the rays emitted by the sources of light that are usually employed, e., an ordinary searchlight. An exception must however be made in the case of the fluorescent aniline colouring matters of the triphenylmethane group which are derived from phtallic acid (eosines, rhodamines), these colouring matters having the property of gleaming or sparkling with a great brilliance in the dark when illuminated by light containing violet rays. These colours are accordingly not used.

For colouring this transparentV coat it is preferred to employ the red colouring matters of alizarine acid which are derivatives of anthranilic acid converted into barytic lakes or others, and precipitated upon pure uncalcined hydrate of alumina.

'For constituting the coloured coats applied in the' improved process, use may be made of all coloured or colouring products of any kind, paints, fatty varnishes, celluloid, cellulose esters, insoluble gelatine, and especially cellulose esters, etc.

In applying the improved process to the aeroplane fabrics it is preferred to employ coloured coating composition having a base point,

of cellulose acetate, also containing as.

specified` in my earlier patent application filed January 10, 1916, Serial No. 71,201, the following essential substances:

a-a dilute solution of cellulose acetate in methyl acetate or acetone solvent, for

ing skin.

c-a softening body such as tri-acetin, in small amount, for instance 0.5 to 1%.

d-a solvent having a very high boiling in the proportion of for instance about 2%. This should bevone which does not evaporate durin the process, such as eugenol orisoeugeno which has the function of increasing the plasticity of the composition, and is itself capable of undergoing certain transformations by way of poly-v y merisation.

e-inert coloured matters (or pigments) serving as the tensioning agent in the very flexible coating skin thus produced; said inert coloured matters being employed in the proportion'of about 1 to 3%. As examples of such pigments, lamp black or Paris blue are mentioned.

As specified in the earlier Patent application of the present applicant 123,640 filed October 4, 1916, this flexible coating skin which is composed of the above specified substances', is imprisoned between two relatively non-plastic rigid coats of composition, such for example as cellulose acetate.

I have now described by way of example a manne` of carrying out the improved process in its applicatlon for coating aeroplane fabricsv and preventing their visibility when they are illuminated by searchlights in the dark. j

This practical example consists in applying successively the following coats:

1.-A rigid non-plastic coat of cellulose acetate which does not contain inert substances, and which has a tensioning effect upon the. fabric (e. g., cellulose acetate alone).

2.-A coat having a matte and darkcoloured coat, having an opaque ground consisting of a liexible composition comosed of the substances specified above uner a, b, c, d and e, in which black or blue pigments sugh as lamp black, Paris blue (or a plurality of such), are employed as the inert ingredients.

3.--A transparent coat likewise consisting of a flexible composition composed of the same substances as specified under a, b,

c, (l and e, but wherein the inert ingredient is constituted by a lake of alizarin red, or any other similar lake which is very rich in colouring matter, precipitated upon hydrate of alumina and containing no mineral loading material whatever. The lake and the h drate of alumina must be very pure in or er that the boat shall be highly transparent.y y

L -A coatof a ltensioning rigid composition whiclrioes not contain any inert matter, and is similar to the composition constituting theV first coat. When the`process is applied to objects besides aeroplane fabrics, such as for instance to vessels, any suitable paints may be employed which are capable of producing by their superposition the above defined optical effect. In such a case the coats that are employed need not have the plastic and tensioning properties vwhich are necessar for treating aeroplane fabrics.

he improved process may also be carried out by the application of a. number of successive coats of monochromaticl transparent varnishes of different colours, capable of absorbing respectively the, various rays of different colours of which the projected beam of light is composed.

It is to be understood that the composition of the coats and their colouring may vary according to the applications, the nature of the objects, and the nature of the source of the projected light. p

The accompanying drawing shows two of the various forms of coatings embraced within the scope of the present invention, the figures being exaggerated sections.

Fig. 1 shows an aeroplane wing fabric impregnated and coated with cellulose acetate, then having a layer of a rst coating, then a layer of a second composition, and then another layer of cellulose acetate.`

Fig. 2 shows a solid article, such as a ship, with a two-layer coating forming a simple example of the present invention.

1. A process for diminishing the visibility of objects and preventing their being picked up by an artificial beam of light, consisting in applying'a first coat,called ground coat, composed of an opaque varnish or composition having a matte surface and a dark colour and then a transparent or translucent coloured varnish, the colour of which bears such a relation to that of the ground coat and to the character of the artificial beam of light, that the greater part of the rays of the projected light beam wfill be arrested and a product of low visibility produced.

2. A process for diminishing the visibility of objects and preventing their being picked up by an artificial beam of light, consisting in applying a ground coat composed of dark coloured opaque pigments, of blue to black shades, incorporated in a vehicle capable of producing a film-coating; and then applying a transparent coat carrying a red lake. the colors of such two coats being such as to substantially lower the visibility of the object coated.

3. A process for diminishing the visibility of-objects and preventing their being picked up by an artificial beam of light, consisting in applying a ground coat composed of dark coloured opaque blue-to-black pigments, in-

' corporated in a vehicle including a cellulose are struck ester and solvents therefor, and then applying a transparent coat carrying a red lake of alizarin precipitated upon pure hydrate of alumina. V

4. A process for coating aeroplane fabrics and preventing their visibility when they are struck at night by the beam of light of a searchlight, consisting in applying a dark coloured, matte, opaque coating having a basis of cellulose acetate and containing a coloured inert substance 'producing a tensioning effect, and in" thereafter applying a transparent coating also having a basis of cellulose acetate, containing an inert substance producing a tensioning effect and comprising a red alizarin lake precipitated upon pure hydrate of alumina.

5. A process for coating aeroplane fabrics and preventing their visibility when they at night by the beam of light of a searchlight, consisting in applying a dark coloured, matte, opaque coating having a basis of cellulose acetate, and containing a dark blue-to-black coloured inert substance producing a tensioning effect; and in then applying a transparent coating having also a basis of cellulose acetate and containing an' inert substance producing a tensioning effect and comprising a red alizarin lake precipitated upon pure hydrate of alumina; each of the coloured and respectively opaque and transparent coatings being composed of a dilute solution of cellulo acetate in a volatile solvent thereof, a so vent having a higher boiling point, serving as any antiroughening agent, a softening substance, and a solventhaving a very high boiling vpoint also serving as plasticifying agent.

6. A process for coating aeroplane fabrics and preventing their visibility when they are struck at night by the beam of light of a searchlight, consisting in applyin a dark coloured, matte, opaque coating aving a basis of cellulose acetate and containing a dark blue-to-black coloured inert substance producing a tensioning effect; and in then applying a transparent coating having also a basis of cellulose acetate and containing an inert substance producing a tensioning effect and substance comprising a red alizarin lake precipitated upon pure hydrate of alumina, each of these coloured and respectively opaque coats being appliecl between two substantially rigid non-plastic coats.

7. A process for diminishing the visibility of objects and preventing their being picked up by an artificial beam of light, consisting in applying a first coat composed of a dark coloured, matte, opaque coating composition; then a plurality of successive coats of coating compositions which are transparent or translucent, monochromatic, differently coloured, and capable of absorbing respectively the various rays constituting the beam of light.

8. A coated article of loW visibility, such article having a coating carrying dark blueto-black pigment and having a matte surface. and Ya superposed coating carrying a red lake, the colors of such coatings being so related as to produce a lowered visibility in the article, as compared with the same article having the same first coating only.

k9. A coated article possessing low visibility comprising an article having a ground coating composed of dark colored matte opaque blue-to-black pigments incorporated in a vehicle including a cellulose ester and a substantially non-volatile li uid solvent and a plasticifying agent; an a superposed transparent to translucent coating comprising a red alizarin lake precipitated upon hydrate of alumina, carried in a cellulose ester.

10. A coated aeroplane fabric of low visibility comprising a fabric carrying a dark colored matte opaque coating having a basis of cellulose acetate and containing a dark blue-to-black pigment capable of producing a tensioning effect; and a superposed transparent to translucent coating having a basis of cellulose acetate and containing an inert material capable of producing a tensioning effect and comprising a red alizarin lake precipitated upon hydrate of alumina.

11. A coated aeroplane fabric of low visibility comprising a fabric carrying a dark colored matte opaque coating having a basis of cellulose acetate and containing a dark blue-to-black pigment capable of producing a tensioning effect; and a superposed transparent to translucent coating having a basis of cellulose acetate and containing an inert material capable of producing a tensioning effect and comprising a red alizarin lake precipitated upon hydrate of alumina, said two coatings being imprisoned between films of cellulose acetate.

12. A coated aeroplane fabric of low visibility comprising a fabric carrying a dark colored matte opaque coating having a basis of cellulose acetate and containing a dark blue-to-black pigment capable of producing a tensioning effect, together with a substantially non-volatile solvent capable of serving as an anti-roughening agent, a softening substance and a plasticifying agent; and a superposed transparent'to translucent coating having a basis of cellulose acetate and containing an inert material capable of producing a tensioning effect and comprising a positions, Which are capable of absorbing 10 red alizarin lake precipitated upon hydrate respectively the various rays of Which a of alumina. beam of light. is composed.

A oated aeroplane fabric coripriinlg Signed by me, this 23rd day of May, 1918. a a ric ase a coatin composed o a ar colored, matte, opaquegcoating composition; THEODORE FRANQOIS TESSE' and a plurality of successive superposedl Witnesses: coats of transparent to translucent monon CHAs. P. PRESSLY, chromatic, differently colored coating comy EMILE BERTRAND. 

